Cyclone with in-situ replaceable liner system and method for accomplishing same

ABSTRACT

Cyclones having abrasion resistant liners with a system and method for replacing the liners when they worn out due to the destructive nature of the materials being classified in the cyclone. The cyclone includes segmented inlet housing liners which are separately removable through the opened top of the cyclone housing. A lifting ring in the bottom of a conical housing has an apex cone and plural cone liners supported in a stacked array thereon within the conical housing and hoisting straps are used to lift the lifting ring, the apex cone and the array of cone liners out of the opened top of the cyclone housing without having to remove the cyclone from its operating position and completely disassemble the cyclone. Wear detector bolts attach the inlet head liners and a cage-like conical housing allows direct viewing of wear detecting weep holes provided in the liners mounted therein.

CROSS REFERENCE TO A RELATED APPLICATION

This application is a divisional application of prior application Ser.No. 10/716,711 for Cyclone with in-situ liner replacement system andmethod of accomplishing same, filed on Nov. 19, 2003 now U.S. Pat. No.7,185,765 by the same inventor.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates in general to cyclones and more particularly toespecially configured cyclones with a liner system and method by whichworn liners are replaced with a minimal expenditure of time and laborand without having to remove the cyclones from their mounting bases.

2. Description of the Prior Art

Cyclones are mechanisms that are used in various industries to separatedifferent sized particles that are fed as a mixture into the inlet ofthe cyclone. In the mineral processing industries such as for example inthe processing of copper, iron ore, lead/zinc, gold, coal and the like,a plurality of large cyclones are typically carried in mounting basesarranged in a cluster over a “tub”. Each of the cyclones are in circuitwith grinding mills and a slurry of water and the mineral to beclassified is fed into the inlet of the cyclone. The heavier materialsin the slurry exit the cyclone through an underflow outlet at the bottomof the cyclone and are returned to the grinding mill. The lightermaterials are carried upwardly in a vortex created within the cycloneand exit through an overflow outlet nozzle at its upper end. The primarycomponents of a cyclone include an inlet housing having a feed duct anda cylindrical head section, a head section cover plate, a downwardlytapering conical housing depending from the head section, an apex coneat the lower end of the conical housing with the course materialunderflow outlet at the lower end of the apex cone, and an internalvortex finder coupled to the fine materials overflow outlet nozzle.

The feed duct of cyclones is often referred to as an involute whichreceives the slurry at high velocity from the grinding mill and directsit tangentially into the cylindrical head section of the cyclone. As theslurry swirls around in the head section the weight of the slurry, andparticularly the large particles, will tend to fall downwardly into theconical housing of the cyclone. The larger particles and the watercarrying them will move downwardly through the apex cone and will exitthe cyclone through the underflow outlet. A vortex consisting of smallerparticles and the water carrying them is created within the apex coneand moves upwardly through the center of the conical housing into thevortex finder and exits the cyclone through the overflow outlet.

The feed duct, inlet head section, head section cover plate, conicalhousing, apex cone and the vortex finder of large cyclones of the typeused in mineral processing are provided with liners which protect thesecomponents from the destructive forces imparted by highly abrasiveslurries as they move through the cyclones.

As disclosed in a paper entitled “Krebs Elastomer Liner InstallationInstructions”, which is available on the internet at the krebs.com website, gum rubber is the most commonly used liner material and syntheticrubber materials are also used in applications where gum rubber is notwell suited. Such synthetic rubber-like materials include Neoprene,Nitrile/bunaN, Butyl, urethane and the like. Elastomeric liners aremolded structures which historically are provided with annular flangesthat are secured between the mating flanges of the different cyclonehousing components to hold the liners in place. It is a common practiceto affix these molded liners to the interior walls of the cyclonecomponents by means of a suitable adhesive. The liners are designed tobe a form fit within their respective components and compressive forcesare used to install and fit the liners within each of the housingcomponents and these forces must be maintained while the adhesive cures.In large cyclones, such as those having head section diameters of 26,30, 33 inches, the conical housing is an assembly usually formed of twoor more cone shaped housings which are bolted together at their matingflanges, and the conical housing assembly is similarly bolted to thelower end of the cylindrical head section after the large one pieceliner is installed in the head section. The apex cone is bolted to thelower end of the conical housing assembly in some cyclones while othersare attached by a quick release clamp as disclosed in my U.S. Pat. No.4,541,934. In liner replacement operations involving these elastomericliners, the cyclone housing must be disassembled, that is, the apexcone, the two or more cone shaped housings which form the conicalhousing assembly and the inlet housing are separated from each other andthe head section cover plate is removed. This provides the access neededto peal the worn liners out of the several cyclone housing componentsand subsequently to apply the adhesive, install the new liners and exertthe compressive forces needed to fit new liners.

As hereinbefore discussed, gum rubber is the most commonly used linermaterial and this is due to it providing the longest possible wear lifein most applications. Alternative liner materials are used inapplications where natural gum rubber is unsuitable. Synthetic rubber isused when temperature or the slurry constituents do not allow the use ofnatural gum rubber. Reinforced highly resilient urethane in used inapplications in which rubber liners are torn rather than worn. Ceramicand silicone materials are typically used in high wear areas of thecyclone and, for example, in the coal industry such liner materials areused throughout the entire cyclone. As was the case with the replacementof rubber liners, the entire cyclone must be disassembled to accomplishreplacement of the liners formed of these alternate materials. Typicalinstallation of such liners is discussed in a paper entitled“Installation of Ceramic Parts into Krebs D-Series Cyclones” which isavailable on the internet at the krebs.com web site. These types ofliners are molded or cast and are assembled and fit individually intothe disassembled housing components which form the cyclone. The inlethead section liner is a large one piece structure which is inserted intothe inlet head housing and rubber wedges are used to center the liner inthe head section. The cover plate and cover plate liner is then mountedon the inlet housing which is turned upside down. The liners areinserted into the cone shaped sections and gaskets and spacer rings arethen inserted sequentially between the flanges which join the inlet headsection to the uppermost cone portion, and between the flanges whichjoin the two or more conical sections to each other. The gaskets aresized so that the abutting edges of the liners are in contact with eachother and a bead of silicone sealant is applied to the abutting edges toaid in sealing the joints. The liner is then inserted into the apex coneand it is then connected to the lowermost cone section of the conicalhousing. The cyclone is then set on its side and the feed duct andvortex finder are then attached to complete the reassembly of thecyclone.

Disassembly of large cyclones for the purpose of replacing worn linersis very labor intensive and time consuming. The first problem associatedwith such operations is the need for removal of the cyclone from itsmounting base in the cluster of cyclones and transporting it to adedicated repair facility or simply laying it on its side in a suitablemaintenance area away from the cluster. Cyclones of this type are veryawkward and can weigh up to about 5,000 pounds. Thus, the operator ofthe crane needed to remove and transport the cyclone must be careful notto damage the cyclone or adjacent equipment and must be skillful toprecisely align the cyclone for reconnection to the material handlingpipes when it is being returned to its operational position. The secondproblem in such operations is removal of the multiplicity of nuts andbolts which hold the various cyclone components together and typicallythe nuts and bolts will number between 50 and 75 depending on the sizeof the cyclone. There are some places on cyclones where power tools willnot fit and in all cases the cyclones which are laying on their sidesduring this phase of the replacement operation must be moved to providethe needed access. Further, due to the hostile environment in whichcyclones operate, the nuts and bolts are often rusted and must in manyinstances be heated or cut off to remove them.

The traditional way to determine when cyclones are in need of linerreplacement is to periodically inspect the liners until accurate recordsof the wear characteristics are collected at which time replacementschedules can be established based upon operating time. Conductingperiodic inspections of the liners is labor intensive in that access tothe interior of the cyclones is needed to conduct the inspections and ofcourse operation of the cyclone must be interrupted during theinspections.

Therefore, a need exist for a new and useful cyclone with a specialliner replacement system and method which overcomes some of the problemsand shortcomings of the prior art.

SUMMARY OF THE INVENTION

The present invention discloses cyclones having a special linerarrangement for in-situ replacement of worn out liners which eliminatethe need for completely disassembling the cyclone housing during a linerreplacement operation. Also disclosed is a method for accomplishing thein-situ liner replacement.

The special liners each include a rigid substrate formed of suitablematerial such as metal, rigid urethane or the like, with an abrasionresistant material such as rubber, high energy (soft) urethane, ceramicor other suitable liner material bonded to the substrate. The substratesare manufactured so as to conform to the shape of the particularinterior wall section of the cyclone housing adjacent to which they willbe placed, and the abrasion resistant materials are bonded to theinterior surfaces of the substrates.

The slurry inlet housing of the cyclone includes a transition ductportion which converts the slurry flow from a round in-cross-sectionflow provided by a supply pipe from the product grinding mill to thesquare in-cross-section flow within a feed duct section of the inlethousing. The feed duct, is sometimes referred to as an involute due toits shape and it feeds the slurry to be processed tangentially into thecylindrical head section of the inlet housing. The liner used in thetransition duct section of the slurry inlet is especially configured toproduce the change in flow configuration and is a one piece structurehaving a flange which is disposed between the flanges of the supply pipeand the transition duct section. At least three separate liner segmentsare used in the feed duct and the cylindrical head section of the inlethousing, rather than the prior art one piece liner, to facilitateinstallation, fitting and subsequent removal. The liner segment used inthe feed duct is configured in the involute shape of the duct and is ofupwardly opening U-shape in-cross-section so that when installed it willline the bottom and side walls of the feed duct. The liner segments usedin the cylindrical portion of the head section of the inlet housing areof arcuate configuration to line the interior side walls of thecylindrical head section of the inlet housing. The open top of the feedduct and the head section are closed by a cover plate and a cover plateliner which is located in the upper end of the inlet housing below thecover plate.

The cyclone housing also includes a cylindrical vortex finder mounted inthe cover plate so as to extend axially down into the head section ofthe inlet housing. The vortex finder is fabricated with a rigid urethanesubstrate to which suitable abrasion resistant exterior and interiorliners are bonded. When the vortex liners are worn out, replacement isaccomplished by removing attaching bolts an pulling the finder axiallyout of the cover plate.

The feed duct liner and the arcuate liner segments used in the inlethousing of the cyclone are held in contiguous engagement with theinterior surfaces of their respective sections of the inlet housing byspecial fasteners. In addition to securing liners in place the specialfasteners act as wear detection devices which provide an indication thatliner wear is nearing the point that a replacement operation should bescheduled. The head section housing is provided with an opening at eachlocation that a special fastener is to be used, and a bolt is positionedto extend through the opening into threaded engagement with a captivenut mounted on the interior surface of the rigid substrate of the liner.The nut is affixed to the substrate prior to bonding of the abrasionresistant material on the substrate and the bolt is sized so that itsinner end is at a predetermined depth within the liner material. Thebolt has an axial bore formed there through so that when the bondedliner material wears to a point where the inner end of the bolt isexposed, a small amount of the slurry will leak out through the bolt andthus provide a visual indication on the exterior of the cyclone housingthat liner replacement will soon be needed.

The cyclone housing further includes a conical housing assembly whichtapers downwardly from its relatively large upper end to its smallerlower end and is dependingly attached to the open lower end of the headsection of the inlet housing. The liners used in the conical cyclonehousing include an upper cone liner, a middle cone liner and a lowercone liner and a apex cone. The upper and middle cone liners arepreferably made with a high energy (soft) abrasion resistant materialsuch as urethane bonded to the rigid substrate as described above andmay be described as “drop-in” structures which fit in their properpositions within the conical housing due to the matching taperedconfigurations of the housing and the liners. The lower cone and theapex cone are preferably provided with ceramic liner materials whichtogether taper from the upper end of the lower cone to a cylindricaloutlet at the bottom of the apex cone. The rigid substrates of the lowercone and the apex cone are of special configuration by which the upper,middle, lower cone liners and the apex cone can be extracted from theconical cyclone housing by a lifting device which will be describedbelow. The upper end of the outer surface of the rigid substrate of thelower cone liner is of conical configuration with the lower portionthereof being cylindrical. A radially extending annular flange is formedon the apex cone and is positioned to circumscribe the open upper endthereof. The lower end of the apex cone is cylindrical and has anannular groove in its outer surface. When installed in the conicalcyclone housing, the lower end of the lower cone rests on the annularflange of the apex cone and they cooperatively form a cylindricalconfiguration at the junction of the lower cone and the apex cone. Theconical cyclone housing is especially configured to provide acylindrical lower end the open lower end of which is circumscribed by aninwardly extending ring-shaped shelf. The cylindrical configurationformed at the junction of the lower cone and the apex cone is located inthe cylindrical lower end of the conical cyclone housing when the lowercone and the apex cone are mounted therein.

A cylindrical anti-splash skirt of tubular shape is mounted so as todepend from the lower end of the apex cone. The cylindrical body of theskirt is formed of high energy (soft) urethane and an inwardly extendingflange circumscribes the open upper end of the skirt. The inherentlyresilient nature of the skirt material allows it to be installed andsubsequently removed by snapping it onto the cylindrical lower end ofthe apex cone with the flange of the skirt being disposed in the annulargroove of the apex cone. An optional snap-in liner of resilient materialcan be installed inside the anti-splash skirt.

A circular lifting ring is supported on top of the ring-shaped shelfprovided at the lower end of the cyclone housing with the flange of theapex cone resting on the lifting ring. The body of the apex cone and thesplash skirt extend axially downwardly through the lifting ring anddepend from the open lower end of the conical housing. The lower, middleand upper cones are arranged in an axially stacked array on the uppersurface of the flange of the apex cone and will move as an entity whenthe lifting ring is moved upwardly toward the inlet section of thecyclone housing.

A pair of hoisting straps are attached to diametrically opposed sides ofthe lifting ring and extend upwardly therefrom between the exterior ofthe axially stacked conical liner array and the inner surface of theconical cyclone housing. The upper ends the hoisting straps each passthrough a different one of a pair of diametrically opposed slots formedproximate the lower end of the head section of the inlet housing so thatthe upper ends of the straps are stored outside the cyclone housinguntil needed to accomplish a liner replacement operation.

The method of the present invention for in-situ replacement of cycloneliners includes the initial step of disconnecting the slurry supply andoverflow pipes from the cyclone to be serviced followed by the step ofremoving the cover plate and cover plate liner. Prior to removing thecover plate and cover plate liner, the optional step of removing theoverflow nozzle and vortex finder may be accomplished or they can beleft in place and removed along with the cover plate. Then the segmentedinlet head liners and the feed duct liners are removed, followed byfishing the upper ends of the hoisting straps through the slots formedin the head section of the cyclone housing to move them into theinterior of the cyclone head section. Then the upper ends of thehoisting straps are connected to a suitable bail that is coupled to acrane which pulls the hoisting straps, and the lifting ring and thestacked liner array and apex cone upwardly in the cyclone housing. Thenext step is interrupting the upward movement of the lifting ring whenthe upper cone liner clears the open upper end of the cyclone housingand removing the upper cone liner manually from the stacked array ofliners. The next step is restarting the upward movement of the liftingring until the middle cone liner clears the open upper end of thecyclone and halting the upward movement so that the middle cone linercan be manually removed from the stack. The next steps includesrepeating the step of restarting and subsequently interrupting theupward movement of the lifting ring until the lower cone and the apexcone have been removed from the cyclone housing. The cyclone linerreplacement operation is completed by the steps of inspecting the linersand replacing those showing excessive wear with new liners andinstalling them in the cyclone housing by performing the above recitedsteps in the reverse order.

In addition to the special liner arrangement and method for in-situreplacement of worn out-liners, a modified cyclone housing is disclosedas having a one piece open-sided cage-like conical housing with the coneliners contained therein being in plain view. This allows wearindicators provided at various locations in the cone liners and the apexcone to be inspected for indication of wear without interruptingoperation of the cyclone. The wear indicators are in the form of weepholes having their inner ends buried beneath the inner surfaces of theabrasion resistant materials so that when the inner ends of the weepholes are opened into the interior of the cyclone as a result ofmaterial wear, the slurry liquid will seep out of the weep holes andprovide a visual indication that a liner replacement operation should bescheduled. Also, modifications of the cyclone assembly techniques aredisclosed to replace the prior art bolted assembly technique.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view of a cyclone incorporating the features ofthe present invention.

FIG. 2 is a top view of the cyclone shown in FIG. 1.

FIG. 3 is an enlarged fragmentary sectional view taken along the line3-3 of FIG. 2.

FIG. 4 is an enlarged fragmentary sectional view taken along the line4-4 of FIG. 2.

FIG. 5 is an enlarged fragmentary sectional view taken along the line5-5 of FIG. 1.

FIG. 6 is an enlarged fragmentary sectional view taken along the line6-6 of FIG. 1.

FIG. 7 is an enlarged fragmentary sectional view taken along the line7-7 of FIG. 6.

FIG. 8 is a perspective view showing the cover plate, cover plate liner,the feed duct liner and the inlet head liners exploded from open top ofthe cyclone.

FIG. 9 is an enlarged elevational view partially broken away to show thevarious features of the conical housing, the apex cone and the splashskirt of the cyclone.

FIG. 10 is an enlarged fragmentary sectional view of the encircledportion 10 of FIG. 9.

FIG. 11 is a sectional view taken along the line 11-11 of FIG. 9.

FIG. 12 is an enlarged sectional view of the encircled portion 12 ofFIG. 9.

FIGS. 13 a through 13 c are perspective views of the cyclone housingillustrating some of the steps of the method of the present invention.

FIG. 14 is a top view similar to FIG. 2 but showing a second embodimentof a cover plate attachment arrangement.

FIG. 15 is an enlarged fragmentary sectional view taken along the line15-15 of FIG. 14.

FIG. 16 is an enlarged fragmentary sectional view taken along the line16-16 of FIG. 14.

FIG. 17 is an elevational view of the cyclone showing it mounted in anangular disposition with the second embodiment of the cover plate shownin FIG. 14 being open to serve as a ramp in aiding the handling of thecone liners during a liner replacement operation.

FIG. 18 is an elevational view similar to FIG. 1 showing anotherembodiment of the cyclone of the present invention with the cyclonebeing partially broken away to show the various features thereof.

FIG. 19 is an enlarged sectional view taken along the line 19-19 of FIG.18 with portions of the view being broken away to show the variousfeatures thereof.

FIG. 20 is an enlarged view of the encircled portion 20 of FIG. 19.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring more particularly to the drawings, FIG. 1 shows a typicalcyclone which is indicated in its entirety by the reference numeral 14.To insure a clear understanding of the present invention, the basiccomponents and features the cyclone 14 will now be described. Briefly,the cyclone 14 includes an inlet housing 15 having a feed duct section16 and a cylindrical head section 17. The top of the inlet housing 15 isclosed by a removable cover plate 18 having an overflow nozzle 19mounted thereon which is in communication with a vortex finder 20 thatdepends from the cover plate 18 axially into the cylindrical headsection 17 of the inlet housing 15. A conical housing 22, which isusually an assembly including two or more truncated conical housings,depends axially from the cylindrical head section 17 and is disposed sothat its small apex end 24 is at the lower end of the conical housing.The conical housing 22 shown in the accompanying drawings is not typicalin that it is especially configured for reasons which will becomeapparent as this description progresses.

The material to be processed in the cyclone 14 is in the form of aslurry which is a mixture usually of water and a range of differentsized particles which are to be classified in the cyclone. The particlescan be various minerals such as iron ore, coal and the like which aredelivered from a grinding mill (not shown) to the cyclone by a suitablesupply conduit 26 which is shown in dashed lines in FIG. 2. The slurryreceived from the conduit 26 passes through a transition duct section 28located at the inlet end of the feed duct 16. The feed duct 16 issometimes referred to as an “involute” in that, as best seen in FIG. 6,it directs the slurry in a curved flow path to an outlet which istangential to the cylindrical head section 17 of the inlet housing 15.The slurry enters the cyclone 14 at high velocity and swirls around thevortex finder 20 in the head section 17 of the inlet housing 15. Due tothe weight of the swirling slurry, peripheral portions of it, andparticularly the larger particles, will tend to fall downward from thehead section 17 into the conical housing 22 of the cyclone 14. Thelarger particles contained in the slurry will move downwardly through anapex cone 30 of frusto-conical configuration and a splash skirt 32located at the apex end 24 of the conical housing 22 and will exit thecyclone 14 through an underflow outlet 34 provided at the open lower endof the splash skirt. A vortex is created within the apex cone 30 whichcarries a slurry of classified particles and water upwardly through thecenter of the conical housing 22 and the head section 17 of the inlethousing 15 and through the vortex finder 20 and the outlet nozzle 19into a discharge duct 36 that is shown in dashed lines in FIG. 1.

In the mineral processing industry, large cyclones such as those havinginlet head diameters of 26, 30 an 33 inches are normally used and due tothe highly abrasive nature of the slurries, such cyclones are providedwith abrasion resistant liners to prevent destruction of the cyclonehousings. As will now be described in detail, the special liner systemof the present invention significantly reduces, and in some instanceseliminates, the previously described problems associated with replacingworn out prior art liners.

Reference is now made to FIGS. 3 through 8 wherein the multiple liners38, 40 and 42 are shown as being used in the inlet housing 15 instead ofthe prior art one piece liner. The liner 38 used in the feed duct 16includes a rigid substrate 44 to which an abrasion resistant material 46is bonded. The rigid substrate 44 is formed of any suitable materialsuch as metal, fiberglass, rigid urethane or the like, and the abrasionresistant material 46 is preferably a high energy (soft) material suchas gum rubber, synthetic rubber or soft urethane. The liner 38 isconfigured to conform to the involute shape of the feed duct 16 and isof upwardly opening U-shape in-cross-section so as to line the bottomand side walls of the feed duct 16. The involute liner 38 is demountablyfixed in the feed duct 16 by attachment means in the form of specialfasteners 48 which will hereinafter be described in detail. The linersused in the cylindrical head section 17 of the inlet housing 15 areshown as being the two liners 40 and 42, however, more than two can beused. Both of the liners 40 and 42 have a rigid substrate 50 to which anabrasion resistant material 52 is bonded to the inner face of thesubstrate, with the substrate and abrasion resistant material preferablybeing the same as that used in the involute liner 38. The liners 40 and42 are of arcuate configuration so as to conform to the interior surfaceof the cylindrical head section 17 of the inlet housing 15, and thepreviously mentioned special fasteners 48 are used to demountably securethe arcuate liners 40 and 42 in place. The involute and arcuate liners38, 40 an 42 are formed with beveled end edges 54 at each location wherethe liners form a junction with each other to seal the joints at thoselocations.

In addition to mounting the involute and arcuate liners 38, 40 and 42within their respective parts of the inlet housing 15, the specialfasteners 48 briefly mentioned above act as wear detection devices thatprovide an indication that liner wear is nearing the point that areplacement operation should be scheduled. A typical one of thefasteners 48 is seen best in FIG. 7 as securing the arcuate liner 40 incontiguous engagement with the interior wall of the head section 17, andit will be understood that the following description will apply to eachof the special fasteners. Aligned openings 56 and 58 are provided in thehead section housing 17 and in the rigid substrate 50 respectively, anda bolt 60 extends through those openings into threaded engagement with acaptive nut 62 that is welded or otherwise affixed to the interiorsurface of the rigid substrate 50 of the liner. The nut 62 is affixed tothe substrate 50 prior to bonding of the abrasion resistant material 52thereto and when the bonding is accomplished, the nut is buried in thematerial 52. The bolt 60 has an axial bore 64 formed there through andthe bolt is sized so that when in threaded engagement with the nut 62,the inner end of the bolt 60 is at a predetermined depth below the innersurface of the abrasion resistant material 52. When the abrasiveresistant material 52 wears to a point where the inner end of the bolt60 is exposed, a small amount of the slurry will seep out through axialbore 64 of the bolt and thus provide a visual indication on the exteriorof the inlet housing 15 that liner replacement will soon be needed. Theaxial bore 64 formed in the bolt 60 is preferably tapered with its smallend located at the inner end of the bolt to prevent clogging of theaxial bore by particles carried in the slurry. The buried depth of theinner end of the bolt 60 is such that when slurry leakage is seen, asufficient thickness of the abrasion resistant 52 remains so thatimmediate liner replacement is not needed and can be scheduled at aconvenient tine.

A special liner 66 is provided for use in the transition duct section 28of the feed duct 16. The transition duct liner 66 is a one piecestructure molded or otherwise formed of a suitable abrasion resistantmaterial which is preferably the same as the material used in the liners38, 40 and 42. The transition duct liner 66 is configured to change theflow of the incoming slurry from the round-in-cross-sectionconfiguration provided by the supply conduit 26 into thesquare-in-cross-section configuration of the feed duct 16. Thetransition duct liner 66 is formed with a flange 68 at its inlet end andthe liner is held in place by its flange 68 being interposed between theflanges of the feed duct 16 and the supply conduit 26.

As seen best in FIG. 5, the vortex finder 20 is preferably formed with arigid tubular substrate 70 having a flange 72 at its upper end. An innerceramic liner 74 is bonded to the inner surface of the tubular substrate70 and an outer ceramic liner 76 is bonded to the exterior surface ofthe tubular substrate to provide the vortex finder with an extendedlife. The vortex finder 20 is demountably secured within an opening 78formed in the cover plate 18 by having the flange 72 of its rigidsubstrate 70 located between the outer surface of the cover plate 18 andthe flange 80 of the overflow nozzle 19 which is bolted to the coverplate. A liner 82 of suitable abrasion resistant material can be bondedwithin the bore 84 of the overflow nozzle 19.

The involute liner and the arcuate liners 38, 40 and 42 respectively, donot extend all the way up to the opening at the top end of the inlethousing 15. A cover plate liner 86 as seen best in FIG. 8, is preferablyformed with peripheral metal band 88 and an internal frame 89 forsupporting a suitable molded abrasion resistant material 90 having adepending peripheral lip 91. When the cover plate 18 and the cover plateliner 86 are in their assembled positions, the depending lip 91 of thecover plate liner 86 exerts a downward force on the top edges of theliners 38, 40 and 42 to seal the joint there between. The cover plateliner 86 may be simply placed in the open top of the inlet housing 15 orcan be attached to the underside of the cover plate 18 by suitablefasteners (not shown).

The conical housing 22, which is customarily an assembly of two or morehousings of truncated conical configuration, depends axially from thecylindrical head section 17 of the inlet housing 15 and is disposed sothat its small apex end 24 is at the lower end of the conical housing.In the embodiment shown best in FIGS. 1 and 9, the conical housing 22has an upper cone housing 92 and a lower cone housing 94 with the latterbeing of special configuration which will hereinafter be described indetail. The liners used in the conical housing 22 are of truncatedconical configuration and include an upper cone liner 96 which is usedto line the inner wall of the upper cone housing 92 and a middle coneliner 98 which is used to line the inner wall at the upper end of thelower cone housing 94. The upper and middle cone liners 96 and 98 arepreferably made with a high energy (soft) abrasion resistant linermaterial 100 such as high energy urethane which is bonded to a rigidmetallic substrate 102. The upper and middle cone liners 96 and 98 maybe described as “drop-in” structures which fit in their proper positionswithin the conical housing 22 due to the matching tapered configurationsof the cyclone housing and the liners. The inner wall at the lower endof the lower cone housing 94 is lined with a lower cone liner 104. Theapex cone 30 and the splash skirt 32 depend axially from open apex end24 of the conical housing 22. The lower end of the lower cone housing94, the lower cone liner 104 and the apex cone 30 are especiallyconfigured to facilitate replacement of the liners 96, 98 and 104 alongwith the apex cone 30 and splash skirt 32 when those components becomeworn out.

The lower cone housing 94 is of downwardly tapering conicalconfiguration for most of its axial length and deviates fromconventional conical cyclone housings by being formed with a cylindricallower portion 106. An annular ring-shaped shelf 108 extends inwardlyinto the opening at lower end of the cylindrical portion 106 of thelower cone housing 94 and a lifting ring 110 is supported on the uppersurface of the shelf 108. The function and structural details of thelifting ring 110 will hereinafter be described in detail. The apex cone30 has a rigid substrate 112 formed of a suitable material such as rigidurethane with a bonded liner 114 which is preferably formed of ceramicto better withstand the severe abrasive forces that occur within theapex cone 30. An annular flange 116 is formed on the substrate 112 andis disposed to circumscribe the open upper end of the apex cone 30. Theapex cone is of tapered configuration for most of its axial length andhas a cylindrical lower end 118 in the outer surface of which an annulargroove 120 is provided. The annular flange 116 of the apex cone 30 issupported on the lifting ring 110 so that the apex cone depends axiallythrough the opening at apex end 24 of the cylindrical portion 106 of thelower cone housing 94. The lower cone liner 104 has a rigid substrate122 formed of a suitable material such as rigid urethane with a bondedliner 124 which is preferably formed of ceramic to better withstand thesevere abrasive forces that occur in that area of the cyclone. Thebonded liner 124 of the lower cone liner 104 is cone shaped as is theinner surface of the substrate 122, however, the lower portion of theouter surface of the substrate is cylindrical to provide a thickenedwall 126 at the bottom end of the lower cone liner 104. The thickenedwall 126 of the lower cone liner 104 is supported on the upper surfaceof the annular flange 116 of the apex cone 30.

The anti-splash skirt 32 has cylindrical tubular body 128 and is mountedso as to depend from the lower end of the apex cone 30. The tubular body128 of the skirt 32 is formed of high energy (soft) urethane and has aninwardly extending flange 130 that circumscribes the open upper end ofthe skirt body. The inherently resilient nature of the skirt materialallows it to be demountably attached to the cylindrical lower end 118 ofthe apex cone 30 by snapping the flange 130 of the skirt body 128 intothe annular groove 120 of the apex cone. An optional snap-in elastomericliner 132 can be installed inside the anti-splash skirt 32, and will besupported by an inwardly extending circular flange 134 formed at thebottom end of the skirt body 128.

As seen in FIG. 11, the lifting ring 110 has a pair of notches 136formed at diametrically opposed sides thereof with a pair of upstandingtabs 138 each located in a different one of the notches and attached tothe lifting ring 110 such as by welding. The tabs 138 extend upwardlyfrom the ring 110 and the lower ends of a pair of hoisting straps 140are each attached to a different one of the tabs. The hoisting straps140 extend upwardly between the inner walls of the conical housing 22and the periphery of the cone liners 96, 98 and 104. The upper ends ofthe hoisting straps 140 enter the lower end of the cylindrical head 17of the inlet housing 15 and pass through slots 142 in the housing to theexterior of the cyclone 14. The hoisting straps 140, which have suitableconnecting hardware such as D-rings 144 on their upper ends, are storedon the outside of the cyclone housing and are used in liner replacementoperations as will be described below.

As previously mentioned, mounting of the cover plate 18 on the inlethousing 15 exerts a downward force which seals the joint between thedepending lip 91 of the cover plate liner and the upper edges of theliners 38, 40 and 42. That same force is transmitted downwardly to sealthe joints between the cone liners 96, 98 and 104. As seen in FIG. 12,wherein the joint between the upper and middle cone liners 96 and 98 isbest seen, the integrity of the seal formed at that joint is assured byforming an annular groove 146 in the top edge of the lower cone liner 98and installing an O-ring 148 in the groove. It will be understood thatthe groove 146 and O-ring 148 shown in FIG. 12 are intended to betypical of the seal configuration provided at joint between each of theliners 38, 40, 42, 86, 96, 98 and 104.

The cyclone liner replacement method of the present invention includesthe initial step of disconnecting the cyclone 14 from the discharge duct36 and, if the transition duct 28 is to be inspected and possiblyreplaced, slurry supply conduit 26 should be disconnected. The nextstep, which can be seen best in FIG. 8, includes removing the coverplate 18 and the cover plate liner 86. Then the special fasteners 48 areremoved and the feed duct liner 38 and the arcuate liner segments 40 an42 are lifted out of the inlet housing 15. In that there are threeseparate liners used in the inlet housing 15 each is relatively lightand can be removed by hand. Referring now to FIGS. 13 a through 13 c,the next steps include fishing the hoisting straps 140 through the slots142 into the interior of the inlet housing 15 followed by the step ofconnecting the D-rings 144 of the straps to the opposite ends of a bail150. A suitable lifting mechanism, such as a crane (not shown), is thenoperated to move the bail 150 and axially pull the stacked array ofliners 96, 98, 104, the apex cone 30 and the anti-splash skirt 32 to afirst position wherein the upper cone liner 96 is clear of the open topof the inlet housing 15 as seen in FIG. 13 b. Upon reaching this firstposition, operation of the lifting mechanism is interrupted and theupper cone liner 96 is manually removed from the stacked array.Operation of the lifting mechanism is then sequentially resumed andinterrupted to move the stacked array into second and third positions(not shown) wherein the cones 98 and 104 are in turn removed manuallyform the stacked array. Final operation of the lifting mechanism raisesthe apex cone 30 and the anti-splash skirt 32 clear of the housing 22 asseen in FIG. 13 c. The liner replacement operation is completed by areversed sequence of the above described steps of the method of thepresent invention.

In view of the disclosed liner replacement system of the presentinvention, it will be noted that the only disassembly now required isremoval of the cover plate 18 and the bolts securing the cover plate.Reference is now made to FIGS. 14, 15 and 16 wherein clamping means 152and hinges 154 are shown which attach a cover plate 18 a to the inlethousing 15. As seen in FIG. 14, a plurality of the clamping means 152are used to secure the cover plate 18 a. The clamping means 152 can beover-center latches, however, the swing bolts 152 as seen in FIG. 15 arepreferred. The swing bolts 152 are mounted to the side of the inlethousing 15 by a clevis 156 which supports an axle 158. A sleeve 162 isprovided on the lower end of the bolt 160 and the sleeve is mounted onthe axle 158 so that the bolt 160 is pivotable between the solid anddashed line positions. In the solid line position, the bolt 160 extendsupwardly through outwardly opening slots 164 formed in the flange 166 ofthe inlet housing 15 and in the cover 18 a. A nut 168 is threadinglymounted on the bolt 160 to hold the cover in the mounted position, andloosening of the nut allows the bolt to be swung into the dashed lineposition. The cover 18 a can be attached to the inlet housing 15 byusing only the swing bolts 152, however it is preferred that the hinges154 be used for reasons which will be described. The hinges 154 may bemounted in the position shown or any other suitable position with thestructural details being shown in FIG. 16. A gusset 170 is mounted onthe side of the inlet housing 15 and a hinge pin 172 extends oppositelyfrom the gusset. A hinge plate 174 is mounted fast on the upper surfaceof the cover plate 18 a and a spaced apart pair of L-shaped arms 176 arecarried on the hinge plate. A sleeve 178 is mounted between thedepending ends of the L-shaped arms 176 with the hinge pin 172positioned in the bore 180 of the sleeve to allow the cover plate 18 ato be moved from the closed position to an opened position as indicatedby dashed lines.

In some installations cyclones are mounted in an inclined position asshown in FIG. 17. In such positions, the cover plate 18 a can be swunginto the open position so that it rests on the cyclone supportingstructure 182. When in this position, the cover plate 18 a acts as aramp to aid in the handling of the cone liner 96 and the other coneliners handled during replacement operations. In some installationsopening the cover plate 18 a in this manner may not be possible andcomplete removal of the cover can be accomplished by removing the hingepin 172.

When retrofitting existing cyclones to include the in-situ linerreplacement system of the present invention, no changes need to be madein assembling a cyclone housing by bolting the plurality of housingcomponents to each other. However, as a direct result of the linerreplacement system of the present invention, new and improved cyclonehousing assembly techniques and design will now be disclosed.

In a first embodiment, a change in the assembly technique is made bywelding the separate components to each other as shown best at 184 inFIG. 9. In addition to eliminating the use of bolts, washers and nuts,using gaskets between the mating flanges will also be eliminated and thechances for developing leaks at the joints will be substantially reducedif not eliminated.

In a second embodiment as seen in FIGS. 18 and 19, a modified cyclonehousing 186, as hereinbefore described, includes the major components ofan inlet housing 188 having a head section 190 and a feed duct 192. Theopen upper end of the inlet housing 188 is closed by a cover plate 194having an apron 195 with an overflow nozzle 196 mounted on the coverplate, and a conical housing 198 depends axially from the open lower endof the head section 190 of the inlet housing 188. In addition to amodified assembly technique, which will hereinafter be described indetail, the major differences between the cyclone 186 and thosehereinbefore disclosed are in the conical housing 198. The conicalhousing is provided with a flange 200 which circumscribes its open upperend and a sleeve 202 is provided at its lower apex end. The flange 200and the sleeve 202 are interconnected by a plurality of struts 204 whichmay vary in number with it being preferred that at least four of thestruts be provided. In addition, the struts 204 may be tubular as shownor they may be beams of any suitable shape such as I-beams. The struts204 are disposed to taper downwardly from the flange to the sleeve andare radially spaced relative to each other to form the housing 198 intoa cage-like structure having openings 206 about the periphery of thehousing. A ring-shaped shelf 208 is provided at the open lower end ofthe sleeve 202 and the lifting ring 110 with its upwardly extendinghoisting straps 140 (one shown in FIG. 18) is restingly supported on theshelf. The annular flange 116 of the apex cone 30 is in turn supportedon the lifting ring 110 so that the apex cone 30 and the anti-splashskirt 32 depend axially from the conical housing 198. The cone liners96, 98 and 104 are supported on the annular flange 116 of the apex cone30 so as to form the stacked array which is removable in the manner setforth in the previously described liner replacement method of thepresent invention.

The open-sided conical housing 198 provides a clear view of the coneliners 96, 98, and 104 so that weep holes 210 formed at variouslocations in the cone liners are in plain view. It will be understoodthat the following description of the weep hole 210 shown in FIG. 19will apply to all of the weep holes. The weep hole 210 is formed in therigid substrate 102 of the cone liner 98 and extends into the abrasiveresistant liner 100 a predetermined distance so that the inner end ofthe weep hole is buried below the inner surface of the liner 100. Theabrasive nature of the slurry being processed in the cyclone will weardown the liner material 100 to a point where the inner end of the weephole 210 becomes open to the inside of the cyclone. When this occurs asmall amount of the slurry liquid will seep out through the weep hole210 and provide a visual indication that a liner replacement operationshould be scheduled.

The cyclone housing 186 has a plurality of swing bolt assemblies 212each including a clevis 214 that is mounted on the flange 200 of theconical housing 198. An elongated bolt 216 having a nut 218 threadinglycarried on its upper end is pivotably mounted in each clevis 214. Eachof the bolts 216 extends upwardly from its clevis 214 through anoutwardly opening slot 220 formed in a load-bearing plate 222 mounted ontop of the cover plate 194. When in the position shown, the swing boltassemblies 212 clamp the cover plate 194 on the inlet housing 188 andclamp the conical housing 198 to the bottom of the head section 190 ofthe inlet housing 188.

As previously mentioned, the upper and middle cones 96 and 98 have asoft abrasion resistant liner 100 such as rubber or high energy urethanebonded to their substrates 102 and the lower cone 104 has a ceramicliner 124 bonded to its substrate 122. Those liner materials arepreferred due to their different characteristics which enable them tobest withstand the different percussion and abrasion forces that occurwithin their particular areas of the cyclone. The different wearcharacteristics of the two dissimilar materials can cause a turbulenceproblem in the cyclone. The liner of soft material wears faster than theceramic liner and when the soft material liner 100 reaches a thicknessthat is less than the thickness of the ceramic liner 124, the top edgeof the ceramic liner will protrude into the cyclone further than thesoft material liner. This is referred to in the industry as a “reversestep” and it produces turbulence by deflecting the downwardly movingslurry into the center of the cyclone which disrupts the flow of slurryand classified materials being carried upwardly by the vortex. Thisproblem is eliminated, or at least substantially reduced, by forming acurved surface 224 on the inner edge of the top surface of the ceramicliner 124 as seen best in FIG. 20. The curved surface 224 is intended toanticipate the wearing down of the soft material liner 100 and may be asegment of a circle or an irregular curve as determined by the wearcharacteristics of the cyclone and the materials being classifiedtherein. It will be understood that a curved surface similar to thesurface 224 can be formed at any junction between dissimilar cycloneliner materials where turbulence resulting from a reverse step couldoccur.

While the principles of the invention have now been made clear inillustrated embodiments, many modifications will be obvious to thoseskilled in the art which do not depart from those principles. Theappended claims are therefore intended to cover such modificationswithin the limits only of the true spirit and scope of the invention.

1. A cyclone having an in-situ abrasive resistant liner removal systemcomprising in combination; a) an inlet housing having open top andbottom ends; b) a feed duct connected to said inlet housing forsupplying materials to be classified thereto; c) a cover plate mountedatop said inlet housing and movable for opening the top of said inlethousing; d) a truncated conical housing depending from the open bottomend of said inlet housing and having an open apex at its lower end; e) aring-shaped shelf at lower end of said conical housing and extendinginto the open apex thereof; f) a lifting ring resting on saidring-shaped shelf; g) a pair of hoisting straps attached todiametrically opposed sides of said lifting ring and extending upwardlythrough said conical housing; h) a frusto-conical apex cone having adownwardly tapering body with an annular flange circumscribing its upperend, the annular flange of said apex cone resting on said lifting ringwith its body depending through the lower end of said conical housing;i) at least one frusto-conical abrasion resistant in said conicalhousing and mounted on the annular flange of said apex cone; and i)means on the upper ends of said hoisting straps for attachment to alifting mechanism for moving said lifting ring, said apex cone andfrusto-conical abrasion resistant cone out of the cyclone when saidcover plate is moved to open the upper end of said inlet housing.
 2. Thecombination of claim 1 wherein there are at least a pair of saidfrusto-conical abrasion resistant cones arranged in a stacked array atopthe annular flange of said apex cone and further comprising; a) thelowermost one of said frusto-conical abrasion resistant cones having agroove formed in its upper edge; and; b) an O-ring in the groove formedin the lowermost one of said pair of cones for sealing the joint therebetween.
 3. 1 The combination of claim 1 wherein said apex conecomprises: a) a rigid substrate having an annular groove formed in theperipheral surface proximate the lower end thereof; and b) a liner ofabrasive resistant material bonded to the inside of said substrate. 4.The combination of claim 3 and further comprising a splash skirtdemountably attached to the lower end of said substrate of said apexcone.
 5. The combination of claim 4 wherein said splash skirt is anelastomeric tubular structure with an inwardly extending flange at itsupper end, said splash skirt being removably snapped in-place within theannular grooved formed at the lower end of said substrate of said apexcone, said splash skirt having an inwardly extending flange at its lowerend with a liner of elastomeric material removably snapped in-placewithin said splash skirt.
 6. The combination of claim 1 and furthercomprising: a) a vortex finder depending from said cover plate into saidinlet housing, said vortex finder including, i) a rigid substrate oftubular configuration; ii) an abrasion resistant ceramic liner bonded tothe exterior of said substrate; and iii) an abrasion resistant ceramicliner bonded to the interior of said substrate.
 7. A cyclone as claimedin claim 1 and further comprising: a) a plurality of clamping meansmounted at spaced apart locations about said inlet housing for movementbetween a cover plate engaged position wherein said cover plate closesthe top of said inlet housing to a cover plate disengaged positionwherein said cover plate is movable to open the top of said inlethousing; and b) hinge means connected to said inlet housing and to saidcover plate for movement of said cover plate between the inlet housingopening and closing positions.
 8. A cyclone having an in-situ abrasiveresistant liner removal system comprising in combination; a) an inlethousing having an open bottom end; b) a cover plate mounted atop saidinlet housing and movable for opening the top thereof; c) a truncatedconical housing depending from the open bottom end of said inlet housingand having an open apex at its lower end; said conical housingincluding, i) a ring-shaped flange attached to the open bottom end ofsaid inlet housing, ii) a sleeve defining the open apex of said conicalhousing, iii) a ring-shaped shelf at the lower end of said sleeve andextending into the open apex thereof, and iii) a plurality of strutshaving upper ends attached to said ring-shaped flange and lower endsattached to said sleeve, said struts being spaced apart relative to eachother to provide said conical housing with a plurality of side openings;d) a lifting ring resting on said ring-shaped shelf; e) a pair ofhoisting straps attached to diametrically opposed sides of said liftingring and extending upwardly through said conical housing; f) afrusto-conical apex cone having a downwardly tapering body with anannular flange circumscribing its upper end, the annular flange of saidapex cone resting on said lifting ring with its body depending axiallythrough the open apex of said conical housing; g) at least twofrusto-conical abrasion resistant cones in said conical housing, saidcones arranged in an axially stacked array atop the annular flange ofsaid apex cone; and h) means on the upper ends of said hoisting strapsfor attachment to a lifting mechanism for moving said lifting ring, saidapex cone and said stacked array of cones out of the cyclone when saidcover plate is moved to open the upper end of said inlet housing.
 9. Acyclone as claimed in claim 8 and further comprising a plurality ofswing bolts mounted at spaced apart locations on said ring shaped flangeof said conical housing for movement between a cover plate engagedposition wherein said cover plate and said conical housing are in aclamped position on said inlet housing and a cover plate disengagedposition for releasing the clamped positioning of said cover plate andsaid conical housing on said inlet housing.
 10. A materials classifyingcyclone having an inlet housing and a downwardly tapering truncatedconical housing, said cyclone comprising: a) a frusto-conical lower conemounted in the conical housing of said cyclone, said lower cone andhaving a substrate with an abrasion resistant liner bonded to the innersurface of the substrate, said lower cone having a top surface; b) afrusto-conical upper cone axially stacked on said lower cone and havinga substrate with an abrasion resistant liner bonded to the inner surfacethereof; c) said abrasion resistant liner of said lower cone having arelatively long resistance to wear in comparison to the resistance towear of the abrasion resistant liner of said upper cone; and d) saidlower cone having a curved surface formed on the inner edge of the topsurface thereof to reduce turbulence produced in said cyclone when thethickness of the liner of said upper cone wears to a thickness which isless than the thickness of the liner of said lower cone.
 11. The cycloneof claim 10 wherein the abrasion resistant liner of said lower cone isceramic and the abrasion resistant liner of said upper cone is anelastomer.
 12. A cyclone for classifying materials, said cyclonecomprising: a) an inlet housing for receiving materials to be classifiedand having an open bottom end; b) a truncated conical housing dependingfrom the open bottom end of said inlet housing and having an open apexat its lower end, said conical housing including,; i) a flange attachedto the open bottom end of said inlet housing, ii) a sleeve defining theopen bottom apex of said conical housing, said sleeve having a lowerend; iii) a shelf at the lower end of said sleeve and extending into theopen apex defined thereby: iiii) a plurality of struts having upper endsattached to said flange and lower ends attached to said sleeve, saidstruts being spaced apart relative to each other to provide said conicalhousing with a plurality of side openings; c) an apex cone having adownwardly tapering body with a flange circumscribing its upper end, theflange of said apex cone resting on the shelf of said conical housingwith its body depending axially through the open apex of said conicalhousing; and d) at least one abrasion resistant liner mounted in saidconical housing and resting atop the flange of said apex cone.
 13. Acyclone as claimed in claim 12 wherein said apex cone comprises: a) arigid substrate; and b) an abrasion resistant material bonded to theinterior surface of said substrate.
 14. A cyclone as claimed in claim 12wherein said abrasion resistant liner comprises: a) a rigid substrate;and b) an abrasion resistant material bonded to the inner surface ofsaid substrate.
 15. A cyclone as claimed in claim 12 and furthercomprising: a) said inlet housing having an open top; and b) a coverplate mounted atop the open upper end of said inlet housing and beingremovable so that said abrasion resistant liner and said apex cone canbe removed from said cyclone when worn out and replacements can beinstalled in said cyclone housing.
 16. A cyclone as claimed in claim 12and further comprising: a) said inlet housing having an open top end; b)a cover plate mounted on said inlet housing for closing the open topthereof; and c) a plurality of swing bolts mounted at spaced apartlocations on the ring shaped flange of said conical housing for movementbetween a cover plate engaged position wherein said cover plate and saidconical housing are in a clamped position on said inlet housing and acover plate disengaged position for releasing the clamped positioning ofsaid cover plate and said conical housing on said inlet housing.